Kawashima Agnieszka T, Wong Cassandra, Lordén Gema, King Charles C, Lara-Gonzalez Pablo, Desai Arshad, Gingras Anne-Claude, Newton Alexandra C
Department of Pharmacology, University of California, San Diego, California, USA.
Biomedical Sciences Graduate Program, University of California, San Diego, California, USA.
Mol Cell Biol. 2021 Feb 23;41(3):e0033320. doi: 10.1128/MCB.00333-20. Epub 2021 Jan 4.
PH domain leucine-rich repeat protein phosphatase 1 (PHLPP1) is a tumor suppressor that directly dephosphorylates a wide array of substrates, most notably the prosurvival kinase Akt. However, little is known about the molecular mechanisms governing PHLPP1 itself. Here, we report that PHLPP1 is dynamically regulated in a cell cycle-dependent manner and deletion of PHLPP1 results in mitotic delays and increased rates of chromosomal segregation errors. We show that PHLPP1 is hyperphosphorylated during mitosis by Cdk1 in a functionally uncharacterized region known as the PHLPP1 N-terminal extension (NTE). A proximity-dependent biotin identification (BioID) interaction screen revealed that during mitosis, PHLPP1 dissociates from plasma membrane scaffolds, such as Scribble, by a mechanism that depends on its NTE and gains proximity to kinetochore and mitotic spindle proteins such as KNL1 and TPX2. Our data are consistent with a model in which phosphorylation of PHLPP1 during mitosis regulates binding to its mitotic partners and allows accurate progression through mitosis. The finding that PHLPP1 binds mitotic proteins in a cell cycle- and phosphorylation-dependent manner may have relevance to its tumor-suppressive function.
PH结构域富含亮氨酸重复序列蛋白磷酸酶1（PHLPP1）是一种肿瘤抑制因子，可直接使多种底物去磷酸化，其中最显著的是促生存激酶Akt。然而，关于调控PHLPP1自身的分子机制却知之甚少。在此，我们报告PHLPP1以细胞周期依赖性方式受到动态调控，并且PHLPP1的缺失会导致有丝分裂延迟和染色体分离错误率增加。我们发现，在有丝分裂期间，PHLPP1在一个名为PHLPP1 N端延伸区（NTE）的功能未明确区域被细胞周期蛋白依赖性激酶1（Cdk1）过度磷酸化。一项基于邻近标记生物素识别（BioID）的相互作用筛选表明，在有丝分裂期间，PHLPP1通过一种依赖于其NTE的机制从质膜支架（如Scribble）上解离，并与动粒和有丝分裂纺锤体蛋白（如KNL1和TPX2）靠近。我们的数据与这样一种模型一致，即有丝分裂期间PHLPP1的磷酸化调节其与有丝分裂伴侣的结合，并允许有丝分裂准确进行。PHLPP1以细胞周期和磷酸化依赖性方式结合有丝分裂蛋白这一发现可能与其肿瘤抑制功能相关。
